Optical device and production method therefor

ABSTRACT

An optical device, such as an optical low-pass filter, and a production method therefor, which prevents damage, and thus maintains optical characteristics are provided. The optical device includes a plurality of optical plates joined together with adhesive. The adhesive is spread to extend to the peripheral edge of the optical plates and to the outer periphery of the principal plane surrounding the plurality of optical plates, thus forming a protective coating.

BACKGROUND OF THE INVENTION

The present invention relates to an optical device and a productionmethod therefor. In particular, it relates for example to an opticallow-pass filter and a production method therefor, which prevents damageduring transportation, while increasing productivity and yield.

Optical low-pass filters are built into various electronic equipmentincorporating optical systems, being located in front of the imager inoptical devices such as cameras, and are used to prevent color blur byutilizing their birefringence. In recent years, electronic equipmentwith built in optical systems are becoming increasingly common, thusincreasing their demand. It is therefore desired to prevent damage sothat optical characteristics can be maintained with certainty, and alsoto prevent negative effects on other optical devices.

FIG. 4 to FIG. 6 illustrate a conventional production example of anoptical low-pass filter.

As shown in FIG. 5, an optical low-pass filter 1 comprises a laminatewhere a plurality of, for example three, optical plates 1 a, 1 b, 1 c,made up from optical plates of chip-form glass or crystal made into aveneer, are bonded together and laminated by an adhesive. For thisadhesive, for example an ultraviolet curing adhesive may be used.

Usually in a conventional production method for an optical low passfilter, firstly as shown in FIG. 4, a laminated wafer is obtained bybonding together and laminating a plurality of optical wafers (composedof glass or crystal) with adhesive, and then dividing this intoindividual laminates by cutting with a dicing saw.

Next, the laminates (optical low-pass filters 1) are manually lined upone by one in a washing device and washed and dried, and then inspectedvisually. Lastly, as shown in FIG. 5, one face (bottom face) of theoptical low-pass filter 1 is affixed to the surface of a double sidedadhesive tape 3 which is also affixed to a mount 2 inside a packing box,and the optical low-pass filter 1 is then stored and shipped in a fixed,inverted position. As a result, damage to the optical low-pass filter 1due to vibrations and shocks during transportation, and coming intocontact with other equipment is prevented.

However, in the conventional production method for an optical low-passfilter as described above, a problem is that the optical low-passfilters (optical plates) 1 consisting of laminates, must be manuallyaligned in the washing device one-by-one by an operator. A furtherproblem is that, as shown in FIG. 5, to individually invert the opticallow-pass filters (optical plate) 1 onto the mount 2 is extremelyinefficient so that productivity and yield is low.

Taking into account these problems, mass automation of the washing andpacking of optical low-pass filters 1 has been devised. However, sincethe optical low-pass filter 1 is composed of brittle material (forexample, glass and crystal), there is a fear of causing damage (such aschipping) to the periphery thereof, particularly in the productionprocess when it comes into contact with automated equipment. Moreover,when the optical low-pass filters 1 are packed, then as shown in FIG. 6,a packing box 4 with small gutters, has these small gutters in bottomedcrevices 5 formed in the packing box 4, and each optical low-pass filter1 is attached for example by the principal plane of the optical low-passfilter 1, into the crevice 5 by automatic transfer from the previousprocess. However, even in this case, the optical low-pass filter 1becomes damaged by colliding with the inner walls of the crevice 5 dueto vibrations during transportation. Such damage causes minute debrisproduced by the damage to adhere to the midsection of the principalplane of the optical low-pass filter, causing deterioration of opticalcharacteristics.

In particular, the optical low-pass filter 1 of the constructiondescribed above, is normally formed by dividing a laminated opticalwafer (laminated wafer) by a dicing saw. In this case particularly thecutting plane (cleavage plane) of the laminated wafer can have minuteand sharp protrusions (burrs), and be jagged. Consequently, theseprotrusions tend to form minute debris by becoming detached from thecutting plane due to shock and vibration. Moreover, such minute debriscan cause negative effects on other electronic devices built intoelectronic equipment.

Here, the optical device is described as a laminated optical low-passfilter, but the same problems generally arise in optical devicesincluding a wave plates comprising veneers.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an optical device and aproduction method therefor, which can prevent damage duringtransportation, and thus maintain optical characteristics.

An optical device of the present invention has adhesive effused andspread on the side faces of a plurality of optical plates. Furthermore,the adhesive is effused and spread so as to span from the side facessurrounding the plurality of optical plates to the outer periphery ofthe two principal planes.

In addition, the present invention is a production method for an opticaldevice involving: spreading an adhesive between the principal planes ofthe plurality of optical plates which form the optical device; pressingthe plurality of optical plates from both principal planes to effuse theadhesive from between the principal planes; effusing and spreading theadhesive onto the side face surrounding the optical plate; and effusingand spreading the adhesive so as to span from the side face surroundingthe optical plate to the outer periphery of the two principal planes.

In the optical device of the present invention, the adhesive which iseffused and spread on the side faces surrounding the plurality ofoptical plates also functions as a protective material, amply preventingdamage to the optical plates during transportation. Furthermore, in theproduction method for an optical device of the present invention, theadhesive is effused and spread spanning to the periphery surrounding theoptical plates and to the periphery of the principal planes, enablingefficient automatic processes to be executed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a flow chart of an example of a production method for anoptical device such as an optical low-pass filter, of the presentinvention.

FIG. 2 is a longitudinal section of an apparatus used in the example ofthe production method for an optical device (optical low-pass filter) ofthe present invention, for capturing and press bonding three opticalplates in a mold.

FIG. 3 is a perspective view of the optical device (optical low-passfilter) of the present invention.

FIG. 4 is a flow chart of a conventional production method for anoptical low-pass filter.

FIG. 5 is a perspective view showing a state after production ofconventional optical low-pass filters, with the filters stored invertedon a base of a packing box.

FIG. 6 is a top view of another example of after production ofconventional optical low-pass filters with the filters stored in apacking box.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An optical device of the present invention comprises, for example, anoptical low-pass filter 1 composed of laminates formed by stickingtogether for example three optical plates (glass, crystal) 1 a, 1 b, 1c, being veneers, with a suitable adhesive.

Here, to produce the optical device (optical low-pass filter) 1, each ofthe three optical wafers made of veneer are firstly cut and dividedusing the dicing saw mentioned above into individual optical plates 1 a,1 b, 1 c, as shown in FIG. 1 and FIG. 2. Next, adhesive 6 is spread ontothe first optical plate 1 a, and the second optical plate 1 b is layeredon top. Then adhesive 6 is spread onto the second optical plate 1 b, andthe third optical plate 1 c is layered on top. These optical plates 1 a,1 b, 1 c are then subjected to bonding and laminating by capturing so asto leave gaps g₁, g₂ inside a mold 8 which can be assembled anddisassembled, being made up of four pushing plates having walls (framewalls) which move in four directions, and having on an inside bottomface thereof a protuberance 7 of square or circular section serving as aholding section. For the mold 8, the planar shape may be C-shape withthe frame wall on one side being movable.

Next, the three optical plates 1 a, 1 b, 1 c layered inside the mold 8are pressed from the upper surface with a predetermined pressure. Thatis, the optical plates 1 a, 1 b, 1 c are pressed between both principalplanes S and S′ so that the adhesive 6 overflows out to the side facessurrounding the optical plates 1 a, 1 b, 1 c. In this case, the gaps g₁and g₂ between the mold 8 and the optical plates are filled withadhesive 6 such that the adhesive 6 circulates to outside both principalplanes (upper and lower surface) of the three optical plates 1 a, 1 b, 1c. In this state, the adhesive 6 is cured by shining ultraviolet rays toform a thin protective coat (for example, of thickness about 20microns). Lastly, the mold is opened in four directions and removed.

Accordingly, an optical low-pass filter can be obtained which hasadhesive spread out to the side faces surrounding the optical plates 1a, 1 b, 1 c. The adhesive may be exuded and spread in minute thickness(for example, of about 20 microns) over the periphery (top and bottomface periphery) of the principal planes of both the upper and loweroptical plates 1 a and 1 c.

According to such a construction, the adhesive 6 which spans the sideface and periphery of the upper an lower principal planes surroundingthe optical plates 1 a, 1 b, 1 c of the optical low-pass filter 1 of thepresent invention, particularly covers and protects each ridge line ofthe optical plates 1 a, 1 b, 1 c. Especially, in this example, since theoptical plates 1 a, 1 b, 1 c are divided by a dicing saw, the resultingsharp protrusions (burrs) on the outside faces of the optical plates arecoated and protected.

Accordingly, even if there are collisions and contact at the time ofvibrations and shocks during transportation of the optical low-passfilter 1, damage of the outer peripheral side faces having protrusionsor burrs can be sufficiently prevented. Therefore, minute debris due todamage is not produced, and minute debris cannot adhere to the principalplanes of the optical low-pass filter, allowing the opticalcharacteristics to be well maintained.

Furthermore, when the principal planes of the optical low-pass filters 1have been attached by vacuum and contained inside the crevices in thetransfer tray or packing box, contact with other transfer apparatus(automated equipment) cannot cause damage. Therefore, the washing andpacking processes of the optical low-pass filter 1 can be automated,resulting in an increase in productivity. Moreover, the adhesive 6 whichbonds the optical plates 1 a, 1 b, 1 c is effused from the surroundingsof the optical plates 1 a, 1 b, 1 c, and spread on the sides and theouter upper and lower faces of the optical plates 1 a, 1 b, 1 c.Therefore, the bonding of the optical plates 1 a, 1 b, 1 c and thespreading process for the protection agent can be performed in a singleprocess. Furthermore, the burrs, unevenness and irregularities on theside faces when the numerous optical plates cut by the dicing saw arelayered together can also be flattened by spreading the adhesive.

In this example of the present invention described above, the adhesivewas effused and spread on the side faces and the outer periphery of theupper principal plane surrounding the optical plate. However, even ifthe adhesive is only effused and spread on the outer side faces, theridge lines of the four side faces and the four corners which arecontacted for example by the fingers of the automated equipment used inproduction, are amply protected by the adhesive. Furthermore, theadhesive 6 was stated as being an ultraviolet curing material. However,it may also be a thermosetting material. Alternatively, thin tape formmaterial may be used instead of adhesive to strap the side faces of theoptical plates to form a protective film.

Moreover, the optical device in the present invention was explained as alaminated optical low-pass filter 1. However this may be applied to anoptical device comprising, for example, a veneer of a wave platecontaining an optical low-pass filter, or an optical device other than alaminated-optical low-pass filter.

Furthermore, the optical low-pass filter (laminate) 1 was formed bycutting three optical wafers into individual optical plates 1 a, 1 b, 1c, and then bonding them together, but it is possible to also bondtogether three optical wafers and then divide them to obtain a laminate.In this case, the laminate can be protected from damage by, at the veryleast, spreading adhesive over the outer side faces of the opticalplates.

Moreover, the cutting and division of the optical wafers was done by adicing saw, but similarly, a scriber can be used to first make a cuttinggroove and the division then performed. Even in this situation, burrscan occur on the outer side faces due to the scriber. Furthermore thelaminate can be formed by mirror polishing the optical plates and thenjoining them, rather than using adhesive.

1-8. (canceled)
 9. A production method for an optical device havingupper and lower principal planes, wherein a plurality of optical platesare bonded together and laminated by an adhesive, the method comprisingthe steps of: cutting and dividing an optical wafer into a plurality ofoptical plates, each plate having two principal planes; spreading anadhesive on at least one principal plane of at least one of saidplurality of optical plates; arranging at least two optical plates in astack, such that adhesive spread in the spreading step is arrangedbetween adjacent principal planes of the at least two optical plates;pressing the stack of optical plates from both principal planes tooverflow said adhesive from between said adjacent principal planes; andeffusing and spreading said adhesive onto an outer peripheral side faceof the stack and into a peripheral region of each of the upper and lowerprincipal planes of the stack, wherein the adhesive between theprincipal planes of adjacent plates is continuous with the coating ofadhesive on the outer peripheral side face of the stack and with thecoating of adhesive on the peripheral region of each of the upper andlower principal planes of the stack.
 10. A production method for anoptical device according to claim 9, wherein said adhesive is overflowedspanning from the side face surrounding said optical plate to the outerperiphery of the upper and lower principal planes of the optical device.11. A production method for an optical device according to claim 9,wherein said adhesive is an ultraviolet curable material.
 12. Aproduction method for an optical device according to claim 9, whereinsaid adhesive is a thermosetting material.
 13. A production method foran optical device according to claim 12, wherein said optical device isan optical low-pass filter.
 14. A production method for an opticaldevice according to claim 9, wherein said adhesive covers the entireperipheral side face of said stack.